Orthogonal frequency division multiple access (OFDMA) communications are known in the art. Such OFDMA systems typically represent data content using so-called OFDMA symbols. In some cases (as with, for example, 802.16e-based OFDMA systems), the tones in a given OFDMA symbol are shared by multiple users. This, in turn, leads to corresponding time synchronization needs as a receiving base station will typically receive a signal that comprises an aggregation of all the presently transmitting end user platforms.
In an attempt to meet this need, each such end user platform typically receives base station instructions (via, for example, a ranging exercise) regarding adjustments to be made to the end user platform's transmissions. These adjustments are intended to cause all end user platform transmissions to arrive in synchronicity at the base station. Unfortunately, such synchronicity typically does not literally occur notwithstanding such adjustments. Ranging errors and channel delay spread as corresponds to each end user platform, for example, tends to cause at least a certain degree of non-synchronicity.
A base station in such a system typically cannot separate end user platform transmissions prior to employing fast Fourier transform processing and therefore must essentially tolerate such timing errors. When the timing error becomes relatively large, however, this typically leads inevitably to performance degradation. Such degradation can often be observed even when, for example, the timing error is small enough to be within a cyclic prefix interval as corresponds to common orthogonal frequency division multiple access protocols.
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